Not sure how tight-knit it is, but it is small enough that you’ll encounter familiar names in chats, running around zones, PUGs, etc. Which like you said is better than being lost in a sea of overpopulation (which feels too much like cross-realm imo).
Could always roll a lvl 1 here and get to a city (or Barrens chat if you’re into that) to get a sense of how many people are around, how active they are, what the AH looks like, etc.
Personally I’m glad I rolled here. Solid community, easy to find groups for questing/dungeons, and best of all, haven’t had to deal with a single queue since I started playing.